Researches of organic light-emitting diodes (OLED) have entered a stage of industrial application presently, research institutes, colleges and enterprises have invested lots of manpower, material resources and financial resources into related researches and applications. Besides of the research and development of light-emitting materials, the research and development of materials with efficient carrier transport function has become something of a hot topic. For now, most organic materials arranged in a p-type structure, which makes the mobility of holes in organic layers much higher than that of electrons and causes disequilibrium of carriers and inefficiency of devices. Therefore, it is urgent to research and develop electron transport materials.
Currently, efficient carrier transport materials are marked by some of the following features: (1) a deeper LUMO energy level, which leads to excellent characteristics of electron injection of the materials; (2) higher electron mobility; (3) a deeper HOMO energy level, which leads to an excellent hole-blocking ability of the materials; (4) a higher triplet energy level (ET), which blocks diffusion of exciton. The widely used electron transport material TAZ (which is represented by the following formula II) cannot meet the above demands, this is because the LUMO energy level and the HOMO energy level of TAZ are −2.7 eV and −6.3 eV, wherein the LUMO energy level is so shallow that it will cause a higher electron injection barrier and a higher driving voltage of a device and is bad for industrialization. The lower electron mobility of TAZ (which is 10−6 cm2V−1S−1) also restricts its application. In addition, the ET of TAZ is only 2.7 eV, which cannot block diffusion of exciton, because of the biphenyl group linking in para position consisted in its molecule.

In recent years, Su etc. have made a detailed and in-depth study on electron transport materials having pyridine groups which shows low LUMU energy level and high electron mobility due to the strong electrophilicity of pyridine. This promotes the development of electron transport materials and the industrialization of OLED greatly.
Based on the above considerations, it is necessary to provide a new electron transport material which can improve the capacity of electron injection, transmitting and hole-blocking, thus can gain high ET and reduce the driving voltage of device, so as to raise the potential of commercial application of electron transport materials.